Axle Code Facts

Q: Rear End Code Facts

I am confused by the codes found on the rear end.

A: After reading all the comments, I thought I’d better give some facts. The 1967 Firebird axle housings have the loops (where control arm bushings would mount) on top of the center chunk as if they were getting A-body control arms, but they also have the spring perches for leaf springs, and the brackets for the factory style “traction bars”. There should also be a date code cast into the center section somewhere. In 1968 they left off the control arm bushing loops and the traction bar mounts, but seemed to use the same codes as 1967. In 1969 the date code position moved from one side of the center section to the other, but I can’t get to my rearend housings to see which are which. Another change from 1968 to 1969 was the addition of flattened spots on top of the axle tubes where the snubbers meet the housing, 1967 and 1968 did NOT have the flat spots. Again, check your cast date codes if at all readable.

Also, all 3 years had the 2-letter stamped code in roughly the same position, about 3-5 inches to the LEFT of the center section, on the rear of the left axle tube (left being the driver’s side of the car). Many times it is obscured by the steel brake line – you’ll need to loosen the clip welded to the axle tube and raise the brake line a bit to see it.

The 1969 codes were different. Here’s the list (first the open ratio, then the posi):

I hope this clears up some confusion and misinformation. Whenever possible, ask about date codes (same style of codes as engine parts), axle codes (rear of left tube), spring perch depth (67 Monoplates are shallow), whether it has the extra brackets for traction bars (67 only), or if there are flattened spots on top (69 only).

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